Improvement in the manufacture of sheet-iron



UNITE STATES- PATENT DANL. L. PRATT, OF BRIDGEPORT, OHIO.

IMPROVEMENT IN THE MANUFACTURE OF SHEETQIRON.

Specification forming part of Letters Patent No. 46,384, dated February 14, 1865.

To all whom it may concern;

Be it known that I, DANIEL L. PRATT, of Bridgeport, county of Belmont, and State of Ohio, have invented new and useful Improvements in the Manufacture of Sheet-Iron and I do hereby declare the following to be a full and exact description of the same.

My object is to produce a perfectly pure article of iron, similar in its characteristics and appearance to the Russian sheet-iron, and which shall be homogeneous, so far as integral quality is concerned, irrespective of an increased den,sity of the surface. I do not seek to efi'ect this by giving a chemically different character to the surface, as has been sought to be accomplished by the addition of carbon in its various forms, such as changing the scale from a ferrate to a protocarbide and incorporatingit withthe iron, or other analogous plans which might be cited. I make no application of an enamel or add anything which chemically combined with the iron arrests oxidization. I claim to produce a pure article which holds inclosed in its pores a material calculated to preserve the iron from the effect of oxygen.

' I take sheet-iron, and after removing the scale I saturate the iron with oil, then roll it, polish, and blue it at a heat which does not expel the oil.

I will now proceed to describe my process with such minuteness that any person skilled in the art to which it appertains will be able to use my invention.

I speak of the sheets in the singular number for convenience, as some of the operations require consecutive handling.

I take common sheet-iron and immerse it in an acidulated bath composed of a solution of organic acid and a mineral acid. I prefer oil ofvitriol. By organic acid I mean such as results from the acetous fermentation .of grain or fruit, or such as pyroligneous acid. I have used vinegar or still-slop which has reached this stage of fermentation. To twenty gallons of the described organic-acid solution of the strength of ordinary household vinegar I add one gallon of the oil of vitriol of commerce. The solution is heated to say 150 Fahrenheit, and the sheet metal may remain in the bath from three to twelve hours. The warming of the solution is donein any suitable manner,such

as afurnace below the copper floor of the tank or acoil of steam-pipe, 850. These are mechani-- cal appliances well understood and not requir--' in gexplicitdescription. The strength and heat of the solution and the time during which the plates shall remain exposed to it are not partia ularly defined, nor would an intelligent work--- sisting of water and carbonate of potash or equivalent alkali. This bath is also at'a temperature of 150 Fahrenheit. Its object is to follow the acid into the pores of the iron and neutralize it. Onehour maysuftice for this. It is then passed between two wheel-brushes, one running above and the-other below the plate, and revolving at a high speedsay five hundred revolutions per minute. Jets ofwater are thrown upon each brush during the process of scrubbing, and the sheets are passed through between the brushes in any suitable manner. The object of this portion of the process is to thoroughly cleanse the surface. It is then placed edgewise in an oven heated to, say, 150 to 200 Fahrenheit, so as to become,pcrfectl y dry. It is then placed in a bath of oil at a temperature of 100 to 150 Fahrenheit. This oil I prefer should be neats-foot, fish, or other animal oil, and free from salt or acid. The sheets are placed in this bath edgewise and out of contact with each other, and may remain--say ten or fifteen minutes-until the pores of the iron are filled with oil. It is then taken out and dripped. The shcetis then passed between a pair of well-polished chillediron rolls until the grain of the sheet isthoroughly rolled down. This has the effect of condensing the surface and closing up the oil in the pores in the interior of the sheet. To roll the sheet at a heat that would evaporate oil would be fatal to this part of my process.

The sheet may be passed through between the rolls several times to complete the operation. The sheet is then passed between two rollers ally to a blue. coal are some of them nearer to the iron than tinge.

Many attempts have been made to produce the mottled appearance, which is nothing more than an irregular color in the sheet, and arises from the fact that the parts were unequally heated.

It is well known that in tempering steel the first color that it receives is a light yellow, and

so passes to a darker, and to a red, and eventu- Now, it the particles of char others, those nearest parts will become the most heated,and the others, being alittle behind, as it may be called, will bear the color next in suit. Thus it may be mottledblue and a-shade of purple derived from the red stage through which it has imperfectly passed. Any mechanical contrivance, such as making 'a hammer-surface to the rollers, so as to give a different reflection to the rays that strike upon y the surfacepf the sheet, is equivalent to makingan irregular surface.

A heated metallic surface of some irregularity may produce the desired effect. I prefer the bed of charcoal.

By a preconcerted arrangement of parts a conformation may be given to the colors of the sheet-waves,patterns, or figures,instead of indiscriminate mottlin I am not aware that mottled appearance is any evidence of value; butit is often seen on the Russian iron, and some desire it. I am not making a mere imitation of anything; but fancies and tastes govern these matters at times, and I am niaking a merchantable article for sale.

The sheet, after coloring, is cleaned with a hand-brush and oiled, so as to preserve it against corroding agents during the transportation or the accidents of storage.

Having thus described my invention, the following is what 1 claim as new and desire to secure by Letters Patent:

1. The herein-described series of processes, substantially as described.

2. subjecting the sheet of iron, after it has been cleansed of its scale and of the operating chemicals and water, to a bath or coating of oil, which is rolled in cold or at a temperature that will not dissipate the oil.

2. Subjecting the sheet, after it has been removed from the bath of alkalin e solution, to the action of revolving brushes, upon each of which a jet or stream of water is thrown.

4. The combination otan organic and mineral acid in the acidulous -bath, substantially as described.

DANIELL. PRATT.

VVi t nesses:

ALEX. A. C. KLAUCKE, EDWARD H. KNIGHT. 

